12v battery low message
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Joined: Sep 2006
Posts: 216
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From: Clear Lake Shores, Texas
2026 AMG CLE 53, 2026 BMW X5, 1972 Corvette
I did a few months ago. I hadn’t been driving the car much plus I was trying to get the digital key to work which involved a lot of engine starting in the garage. I charged the battery and haven’t had any issues since despite the fact it’s still not driven very often.
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Joined: Mar 2013
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From: SWFL
2023 BMW M340i, 2025 MB CLE53 AMG
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Joined: Aug 2014
Posts: 139
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From: SF Bay Area
'08 BMW 335i Coupe '15 E400 Sedan '25 CLE 53 Coupe
A few months after delivery, parked the unlocked CLE in the garage after an evening drive. The next morning my wife mentioned hearing the car’s radio playing. Walked out to find it was operating in an accessory mode overnight. Not sure how it happened since the system should have powered-down shortly after closing the driver’s door upon exiting.
There wasn’t a low battery warning but it did take a very long time for the CTEK tender to bring it back to a full state of charge.
Hasn’t happened since though I sometimes check to make sure when parking the car unlocked (locking a sure way to shut everything down).
xAI chatbot states it’s not entirely uncommon:
“The radio (or full head unit/MBUX) sometimes fails to fully enter deep sleep after shutdown, even when the driver's door is closed and you're out of the car. Displays go blank, but the audio gateway or infotainment module lingers in a semi-active state, drawing enough current (parasitic drain) overnight to drop the 12V battery noticeably.
Since it hasn't recurred, it's probably not a hardware failure (like a bad relay or module) but rather an occasional MBUX software/firmware timing or shutdown sequence glitch - pretty common in early 2024–2025 CLE builds. Mercedes has rolled out several MBUX OTA updates and service campaigns for CLE models addressing black/frozen screens, unresponsive touch, audio issues, and related power-down behaviors (some tied to fault codes like audio tuner malfunctions or data line errors). These often fix the incomplete shutdowns that cause drain.”
There wasn’t a low battery warning but it did take a very long time for the CTEK tender to bring it back to a full state of charge.
Hasn’t happened since though I sometimes check to make sure when parking the car unlocked (locking a sure way to shut everything down).
xAI chatbot states it’s not entirely uncommon:
“The radio (or full head unit/MBUX) sometimes fails to fully enter deep sleep after shutdown, even when the driver's door is closed and you're out of the car. Displays go blank, but the audio gateway or infotainment module lingers in a semi-active state, drawing enough current (parasitic drain) overnight to drop the 12V battery noticeably.
Since it hasn't recurred, it's probably not a hardware failure (like a bad relay or module) but rather an occasional MBUX software/firmware timing or shutdown sequence glitch - pretty common in early 2024–2025 CLE builds. Mercedes has rolled out several MBUX OTA updates and service campaigns for CLE models addressing black/frozen screens, unresponsive touch, audio issues, and related power-down behaviors (some tied to fault codes like audio tuner malfunctions or data line errors). These often fix the incomplete shutdowns that cause drain.”
Last edited by J.Raymond; Feb 8, 2026 at 03:18 AM.
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